The World Health Organization warned world leaders Wednesday that there can be "no going back to business as usual" following the coronavirus pandemic, which has upended economies and wreaked havoc on nearly every country across the globe.

"This virus likes to find opportunities to spread and if these lockdown measures are lifted too quickly, the virus can take off," Dr. Maria Van Kerkhove, the WHO's lead scientist on Covid-19, said during a press conference at the agency's Geneva headquarters. "The only way to control and suppress this virus, this Covid-19, is to actually find [cases], quarantine those contacts, isolate the cases and it will be brought under control."

The coronavirus has infected more than 3.6 million people worldwide and has killed at least 257,818 since it emerged in Wuhan, China over four months ago, according to data compiled by Johns Hopkins University.

WHO Director-General Dr. Tedros Adhanom Ghebreyesus said countries cannot "let preparedness go by the wayside. As we work on responding to this pandemic, we must also work harder to prepare for the next one. Now is an opportunity to lay the foundations for resilient health systems around the world, which has been ignored for long."

While reported cases are beginning to decline in regions such as Western Europe, more cases are being reported every day in Eastern Europe, Africa, South-East Asia, the Eastern Mediterranean and the Americas, Tedros said, adding an average of around 80,000 new cases have been reported to the agency every day.

"These are not just numbers. Every single case is a mother, a father, a son, a daughter, a brother, sister or friend," he said.

Tedros urged caution to countries looking to ease social distancing restrictions intended to curb the pandemic. He said the risk of returning to lockdown "remains very real" if countries do not manage the transition "extremely carefully."

While social distancing measures put in place in numerous countries to slow the spread of the coronavirus have been successful, the virus remains "extremely dangerous," WHO officials said. Current data show "most of the world's population remains susceptible," they said, meaning outbreaks can easily "reignite."